1. Field of the Invention
This invention relates generally to the design of color filter modules in plenoptic XYZ imaging systems.
2. Description of the Related Art
Color filters are commonly used in order to enable color imaging. For example, the Bayer filter is a common arrangement of red, green and blue filters placed directly over a sensor array in order to create RGB imaging systems. The CIE XYZ color space is another formulation of color that has advantage over the more commonly used RGB color space. One advantage of an imaging system using XYZ filters is that the spectral sensitivities of the X, Y, and Z filters are much closer to the CIE standard observer color matching functions (the red, green and blue curves that represent an average human's chromatic response) than those of the R, G, and B filters used in conventional RGB imaging systems. As a result, an XYZ imaging system can reproduce these XYZ values more accurately than a conventional RGB imaging system. However, it is difficult to fabricate good XYZ filters and even more difficult to fabricate XYZ color filters at a size and in a pattern that can be placed over a sensor array. As a result, XYZ imaging systems are not so common, despite the advantages of the XYZ color space.
Furthermore, for colorimetric applications, it is important to define a suitable evaluation metric for the color imaging system. Color accuracy may be evaluated using the Delta-E (ΔE) metric defined in the CIE (International Commission on Illumination) standard. However, due to effects such as noise introduced by the sensor array and variations in the manufacture and assembly of optical systems, use of the ΔE metric alone may be inadequate to evaluate the performance of a color imaging system. Conversely, a color imaging system designed on the basis of the ΔE metric alone may be suboptimal.
Thus there is a need for improvements in designing color imaging systems.